The present invention relates to a solar ray collecting device wherein solar rays passing through a transparent dome are collected by a plurality of solar ray collecting elements.
The present applicant has previously proposed a sun ray collecting device in which the sun's rays are focused by a lens, guided into an optical conductor, and then transmitted through the optical conductor onto an optional desired place for use in illumination or for other like purposes. Furthermore, the present applicant has also proposed that the afore-mentioned sun ray collecting device be accommodated in a transparent capsule in order to protect the lens from wind, rain, dust etc.
The sun ray collecting device previously proposed by the present applicant has a cylindrical foundation, a dome-shaped head portion made of a transparent material, and a capsule for use in the sun ray collecting device consisting of a foundation and a head portion. When the device is being employed, the sun ray collecting device is accommodated inside the capsule. The sun ray collecting device comprises, for instance, a large number of lenses, a large number of lens-holding apparatuses provided for the respective lenses, and a large number of optical fibers or an optical conductor cable having a light-receiving end placed at the focal position of the lens.
The sun's rays focused by the lenses are guided into the optical conductor cable and transmitted through it onto an optional desired place.
In the above-mentioned prior art, since the dome-shaped head is fixed to the cylindrical body, the head must be made to cover the whole area where the solar ray collecting portion follows the sun's movement, and therefore the head must be of a spherical shape of an increased size.
Such a large dome-shaped head is difficult to manufacture and is very expensive. Furthermore, it is impossible to make a head having a precise spherical shape and a uniform thickness. It has also been found that the dome having a partly uneven wall thickness may refract solar rays in various directions in relation to the solar ray collecting portion with the result that there is reduced efficiency in collecting solar rays.